Dispensers for releasing liquid products into the ambient air are well known in the art. These devices may deodorize, humidify, disinfect, emit a fragrance, deliver a medical or cosmetic spray, or distribute toxins into the air to kill and or repel unwanted pests, such as insects. Consequently, each application may require a different type of spray or spray property. For instance, some applications may require smaller droplets with a shorter plume length while others may require larger droplets with a longer plume length. Similar considerations may be made with respect to other attributes such as spray orientation, direction, discharge rate, or the like. Therefore, continuous efforts are directed toward new techniques of dispensing liquid products that may adapt to any and all spray requirements.
Several techniques have been employed to dispense liquid products into the air. One of the more common dispensers includes aerosol dispensers which release pressurized liquid products from gas-filled containers. Common alternatives to aerosol dispensers include atomizers which reduce a liquid product into tiny droplets and or particles to be released into the air as a fine spray. While the dispensers noted above may be useful in releasing liquid products into the ambient air, they have their drawbacks.
Aerosol dispensers have been commonly used to dispense liquid products and are well known in the art. Moreover, aerosol dispensers provide a low cost method of dispensing liquid products in any orientation and direction. In an aerosol dispenser, the liquid product to be dispensed is typically mixed in a solvent and a propellant. The propellant provides a force to expel the liquid when a user actuates the aerosol container. The two main types of propellants used in aerosol containers today are liquefied propellant gases (LPGs), such as hydrocarbon or hydrofluorocarbon (HFC) gas, and compressed gas propellants, such as compressed carbon dioxide or nitrogen gas. To a lesser extent, chlorofluorocarbon propellants (CFCs) are also used.
Propellants that use LPGs share several disadvantageous traits. While the use of CFCs is being phased out due to the harmful effects of CFCs on the environment, many aerosol dispensers still use hydrocarbon propellants. Hydrocarbon propellants contain Volatile Organic Compounds (VOCs) which may have detrimental effects on the environment. The content of VOCs in aerosol dispensers is an unwanted byproduct and is consequently regulated by various federal and state regulatory agencies, such as the Environmental Protection Agency (EPA) and California Air Resource Board (CARB).
Compressed gas propellants also possess disadvantages. Dispensers that use compressed gas propellants exhibit spray attributes that are inconsistent throughout the life of the dispenser. Specifically, their spray performance relies solely on pressure provided by the gas remaining in a container. As the gas is depleted, the spray properties of various dispensers have shown an increase in droplet size and or shorter plume lengths due to the decrease in propellant pressure. In many cases, the lack of propellant pressure leaves excessive amounts of the unused liquid product in the container.
The concept of atomizers that dispense liquids into the ambient air is also well known in the art. In general these devices supply the liquid product to a vibrating perforated plate which, due to its vibrations, consistently breaks up the liquid into fine droplets and ejects them in the form of a mist or a cloud. As the droplets travel, the liquid evaporates from the droplets and disperses into the atmosphere.
One disadvantage to atomizers pertains to the inability to spray in any direction and or orientation. Many of the atomizers do not allow transport of a liquid to the vibrating plate for atomization unless the device is upright. For instance, the capillary in a capillary-based atomizer may not be in fluid communication with the liquid product unless it is situated in the upright position. Additionally, many atomizers are not substantially sealed to prevent leaks or spills when the device is not upright.
Additional drawbacks relate to relatively large discharged particles, low discharge rates and short spray lengths. Dispensing large particles creates situations in which the droplets are too large to effectively evaporate into the ambient air. Subsequently, the droplets may eventually settle on surrounding surfaces to cause more problems than it attempts to solve. Low discharge rates and short spray lengths further limit the atomizer to only certain products and applications. For instance, an atomizer would not be able to spray a fragrance high enough to reach the center of a large room.
Nonetheless, a few advances have shown an atomizer to release smaller droplets of approximately 30 microns. While the droplet size is consistently smaller, the atomizer discharges at rates of only microliters per hour and ejects plume of less than one foot in length. Other advances have shown an atomizer outputting at increased rates of microliters per second and extending plumes to 15 centimeters. However, the reach of these sprays are still relatively short and the atomizers are still unable to spray in any direction and or orientation.
Therefore, multiple needs exist for an improved atomizer for common consumer products that is capable of spraying in any orientation, increases plume lengths, increases the delivery rate, and does not release harmful pollutants into the environment. Additional needs exist for improved atomizing techniques that may be easily adapted for use with a wide variety of applications.